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<script type="text/javascript">
var arr=new Array("《明史讲义》","《明代社会生活史》","《紫禁城的黄昏》","《国史十六讲》","《停滞的帝国》","《唐朝定居指南》","《明史简述》","《明史十讲》","《大明风物志》","《皇帝与秀才》");
var newarr=new Array();
var j=0;
for(var i=0; i<arr.length; i++){
	if(arr[i].length==6){
		newarr[j]=arr[i];
		j++;
	}
}
document.write("书名为4个字的书籍："+newarr.join("、"));
</script>
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